1. Technical Field
Exemplary aspects of the present invention generally relate to a drive transmission unit and an image forming apparatus including the drive transmission unit, and more particularly to a drive transmission unit that switches a direction of rotation of a gear.
2. Description of the Related Art
There is known a drive transmission unit that inputs an output rotation of a motor to an output shaft and transmits the rotation of the motor to a target by rotating the output shaft in a forward and a reverse rotation. Such a configuration is proposed in JP-2010-023983-A, for example. The known drive transmission unit includes two drive transmission paths from a drive-input gear meshing with a gear to which rotation is input from the motor, to a drive-output gear that transmits the rotation to the target. The first path is a path from the drive-input gear to the drive-output gear via a forward-rotation clutch which is engaged upon outputting the forward rotation and is disengaged upon outputting the reverse rotation. The second path is a path from the drive-input gear to the drive-output gear via a counter gear and via a reverse-rotation clutch which is engaged upon outputting the forward rotation and is disengaged upon outputting the reverse rotation.
As described above, the number of intervening gears is different between the first path and the second path, thereby transmitting selectively the forward rotation and the reverse rotation of the drive-output gear while rotating a single motor in a single direction.
The known drive transmission unit includes the plurality of gears. That is, the known drive transmission unit includes the counter gear and the input gears for the clutches, arranged together in the radial direction of the drive-input gear. The output gears for both clutches are disposed in the radial direction. Furthermore, the drive-output gear is also disposed in the radial direction of the output gears.
A drawback to this configuration is that two gear systems having the plurality of gears are disposed from the drive-input gear in the radial direction of the rotary shaft of the drive-input gear, which occupies a significant space in the radial direction.
In view of the above, there is demand for a drive transmission unit that occupies less space in the radial direction of a rotary shaft, and an image forming apparatus including such a drive transmission unit.